1. Field of the Invention
This invention relates to an eye shield to protect ocular structures during electron beam treatment of eyelid tumors.
2. Description of the Prior Art
Protection of the ocular structures of the eye is important in eye surgery and treatments of tissue surrounding the eye. The goal in such procedures is usually both the correction of a medical problem and the preservation of ocular function. Eye shields and related devices have been designed for use in various procedures to meet these goals. Each shield or device was designed to avoid hazards particular to the procedure for which the shield was to be used.
U.S. Pat. No. 4,570,626 to Norris and Schwartz discloses an opaque shield which is of smaller diameter than the cornea. This shield is intended to prevent damage to the retina from bright lights used during optical surgery, for example, during the removal of cataracts. This shield may be constructed of various materials, such as rigid or flexible plastics. Its primary qualities are that it is opaque to visible light and that it is smaller than the cornea.
U.S. Pat. No. 5,021,057 to Byrne discloses a tool for use in closing anterior segment openings and preventing hemorrhages. This tool is characterized by its transparency, allowing the surgeon to visually monitor the eye, and by an opening which allows the surgeon to suture the area underneath the tool.
U.S. Pat. No. 4,990,150 to Tsubota and Sakai discloses a bandage to hold an incision closed without the need for a temporary suture. This bandage is useful during invasive, and especially during protracted, surgical procedures to protect the integrity of the anterior chamber of the eye.
U.S. Pat. No. 4,406,285 to Villasenor and Krasnow discloses a template for use in performing radial keratotomy. The template is shaped to fit over the cornea and provides slits to guide a surgical blade. The slits are designed to provide precise location for the incisions and to regulate the depth of the incisions.
U.S. Pat. No. 4,122,847 to Craig discloses a flexible mask which covers the eyes and a portion of the surrounding skin. The mask is designed for use in surgery to prevent extraneous fluids from being introduced into the patient's eyes. The portion of the mask which covers the eyes is transparent to allow observation of eye condition, for example, by an anesthesiologist.
U.S. Pat. No. 3,973,561 to Kane discloses an eye covering to protect the eyes of large domestic animals in the case of disease or infection. The shield is designed to cover the entire eye and is opaque. It is further designed of a flexible material so it can return to its original shape if deflected.
U.S. Pat. No. 2,415,384 to Bushnell discloses an eye cover for people who have lost an eye. It is designed to cover the entire eye socket and has a base extending into the eye socket for anchoring. The preferred material is thermoplastic or a noncorrosive and nonirritating metal.
U.S. Pat. No. 2,379,629 to Eweson discloses a piston device with a suction cup on the end for use in inserting and removing contact lenses.
Internal eye shields designed for shielding during orthovoltage X-ray treatments are commercially available. Internal, plastic-coated lead eye shields are commercially available from Ace Medical Supply Co., 799 Broadway, New York, N.Y. 10003. Such shields have also been made with a gold coating, although this coating is unstable and may irritate the patient's cornea during treatment.
The foregoing devices solve particular problems associated with certain procedures for eye surgery or other treatment of eye problems. However, they do not provide a solution for the problem of protecting the ocular structures from damage during high energy electron beam treatment of eyelid tumors. None of the patented devices is designed for insertion between the eyelid and the surface of the eye, as is necessary to protect against electrons which are transmitted through the eyelid's tissue. The materials used in the patented shields are selected for transparency or opacity to visible light rather than high energy electrons. Additionally, an eye shield for use during electron beam treatment of eyelid tumors must avoid backscattering of electrons which could burn tissues by increasing the total dosage above clinically acceptable limits. Finally, the commercially available internal shields do not provide sufficient shielding to protect against ocular damage during the use of high energy electron beams.